# Comparison of spirometry, impulse oscillometry, and multiple breath washout in children with primary ciliary dyskinesia

## TL;DR

The study compares three lung function tests in children with primary ciliary dyskinesia and finds that one test detects issues earlier than others.

## Contribution

This is one of the few studies comparing MBW, IOS, and spirometry in children with PCD.

## Key findings

- PCD children showed significant differences in spirometry and MBW compared to healthy controls.
- MBW detected airway anomalies earlier than spirometry in PCD patients.
- LCI 2.5% was abnormal in nearly half of PCD patients with normal FEV1.

## Abstract

Primary ciliary dyskinesia (PCD) is associated with ventilation defects and heterogeneous impairment of pulmonary function. Spirometry alone may underestimate PCD severity and complexity. This study aimed to evaluate spirometry, multiple breath washout (MBW), and impulse oscillometry (IOS) in children with PCD and healthy controls.

In this cross-sectional, prospective study, participants included children aged 6–18 years with PCD and healthy age-matched controls. Pulmonary function tests using MBW, IOS, and spirometry were conducted on the same day for all participants.

Thirty-two children with PCD (cwPCD) (median age 16.5 years) and 44 age-matched healthy controls (median age 15.7 years) were studied. PCD was associated with lower forced expiratory volume in 1 (FEV1) percent predicted (pp), forced vital capacity (FVC) pp, FEV1/FVC, reactance 5 (X5); as well as higher resistance 5 (R5), R10, R15, R20, resonance frequency (Fres) and lung clearance index (LCI) 2.5% mean values (p < 0.05 for all). Abnormal LCI 2.5% was found in 46.5% of patients with predicted FEV1 pp > 80%. Significant inverse correlations were observed between LCI 2.5% and FEV1 pp (p < 0.001, r: −0.62), FVC pp (p = 0.004, r: −0.49), FEV1/FVC (p = 0.002, r: −0.52) in PCD patients.

This is one of the few studies comparing MBW, IOS, and spirometry in cwPCD. The study has shown that there are significant differences in spirometry and MBW between cwPCD and healthy controls. MBW can detect airway anomalies earlier than spirometry and may be used in follow-up as an alternative pulmonary function test in cwPCD.